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No sound after adding ground wire

Discussion in 'Pickups & Electronics [BG]' started by arca_tern, Jan 29, 2019.

  1. So my Fender Jazz (MIM Geddy Lee) had no shielding or ground wire to the output jack.
    I used MG solutions silver paint to do all the cavities and cable routes (both pickups, bridge) and tested them all for continuity. Almost 0 ohms reading. Great!

    I them soldered up the pickups back to the pots, and added a ground.
    The ground was a wire from the output jack crimped + soldered to a ring terminal which I screwed into the conductive paint.

    After re-stringing, I plugged into my tuner to get into the ballpark before checking the truss rod. Only my tuner got nothing. Sat there waiting for a signal.

    I took the control plate off the body and with it still wired, it started to give a signal. I put it back on the body, signal gone.

    My guess was something about the conductive paint touch the control plate and also having the ground to the body on the output jack, as that was really the only wiring change that happened.

    I pulled the new ground wire (unscrewed from the body and desoldered from the jack) and everything works like cherry pie.
    There is no hum anymore with the shielding, so mission accomplished there.

    What went wrong here, and should I leave it as is?
    This was the original wiring.
    It is the same again now (with less pretty soldering)

  2. It sounds like something is shorting out. Do you have pictures of your new wiring and with the cavity shielded?
  3. saabfender

    saabfender Inactive

    Jan 10, 2018
    Why is there no wire attached to the ground lug on the output jack?
  4. pic of shielding below. I didn't take a pic of the new wiring unfortunately.

    it's a photo of the original wiring pre-shielding (as said above). I didn't take a picture of the new wiring and can't as it's unscrewed and de-soldered. I've attached a mockup of the what it was. Hope it helps.
  5. There's no issue right now (shielding worked great - super quiet now) and plays fine. I'm more wondering what the issue was with the added ground. :confused:
  6. It could have been that the tab of the tip was touching either the conductive paint on the bottom of the cavity or the ground ring that you added.
    LowActionHero, TonH and arca_tern like this.
  7. bassdude51

    bassdude51 "You never even called me by my name." Supporting Member

    Nov 1, 2008
    Central Ohio
    Since the control plate is made of metal, the jack is automatically grounded to the pots because they are all electronically connected. So, there doesn't have to be a ground wire to the jack if the pots are already grounded. See diagram.

    As to why you lost your signal, I have no idea. All of your grounding effort with the paint and stuff is not really necessary. Just stick with the way it was in the first place.

    img002copy-jpg.jpg dm9ncx-jpg.jpg
  8. Yeah it wasn’t the ground ring (I check to make sure) but maybe it was the floor of the cavity. That makes sense.

    Yes the jack was grounded to the pots but not the shielding. Some make it best practice to have an actual ground wire to the jack vs relying on the control plate.

    We may just never know. But I’m happy and was a fun job and the most work I’ve done on an instrument of my own. :). Now not as scared to open her up and gut her.
    Spidey2112 likes this.
  9. bassdude51

    bassdude51 "You never even called me by my name." Supporting Member

    Nov 1, 2008
    Central Ohio
    Congratulations on your efforts and ya had a good time and learned a lot. Good for you!

    Do you have a voltmeter? A great way to confirm grounding. So, if ya put one lead on the shielding paint and the 2nd lead on the control plate or bridge or brass thingy at the bottom of the cavity and ya see the meter read a connection, you're good. If no reading, there is a break in the ground connection.

    Same with touching the ground lug on the jack and then to a pot or control plate.

    Just like you, about 20 years ago, I started tinkering with bass electronics. I got anal with shielding and stuff. Now, I just do it exactly the way it was done at the factory at Fender. There's no need to go any farther.

    The Jazz Bass is made with 2 single coil pickups. One is reverse wound and with the magnet poles polarity the other way around. When both pickups on a Jazz Bass are run together, they work like a humbucker. No hum. Play one or the other pickup alone by itself, it hums.

    With or without shielding, the pickups will hum when played by themselves, with or without shielding they will not hum when both played together.

    I just stay with factory wiring and leave it at that.

    Essential tool for bass wiring.

    arca_tern likes this.
  10. DWBass

    DWBass The Funkfather

    I had an issue like that. It ended up being one of the jack plate screws was exposed and the tip of the plug was touching it shorting it out.
    arca_tern likes this.
  11. Thanks! The single coil 60 cycle hum wasn’t an issue. It was downstairs and at church under fluorescent lights. If I wasn’t touching metal on the bass it was nasty hiss. Now it’s gone. The shielding was with it. Not going to bother adding the extra ground again.
  12. BigBear77


    Aug 30, 2017
    Sounds like a dead short. Probably the tip of the jack touching the side of the control cavity or the ring terminal you installed
    arca_tern and Spidey2112 like this.
  13. 96tbird

    96tbird PLEASE STAND BY

    Since you pulled the ground to the shield, the shield isn’t connected, and you get signal. Therefore your jack was shorting when you had the plug in. Problem is, now your shield isn’t grounded so it’s not functional.

    I think your tip solder lug on the jack was contacting the side wall of the route. Or the prong was touching the bottom of the route.

    If you want to try again, lay some electrical tape on the sides and bottom near the jack and connect the ground to the shield again.
  14. Spidey2112


    Aug 3, 2016
    This... control plate on, problem... control plate off, no problem... any signal generated was more likely, than not, going straight to ground...

    ... path of least resistance.

    Most important thing is it's working for you... you have it wired the same as it was, before shielding?
    arca_tern likes this.
  15. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    It was grounded through the control plate. Not the best practice but it would probably never have a problem
    arca_tern and saabfender like this.
  16. bassdude51

    bassdude51 "You never even called me by my name." Supporting Member

    Nov 1, 2008
    Central Ohio
    I hope I've not sounded preachy. 60 cycle hum comes and goes simply by rotating the instrument to the right or to the left.

    I have a single coil P Bass and I play it a lot in front of the TV set. And I mean old TV set since I've not bought a flat screen yet. Anyway, my bass picks up hum from the TV if I get too close. Back away a few feet (non metric here) and the hum goes away.

    You know this already.

    It a wonderful thing for you to play bass in a spiritual setting! I'm happy for ya!
    Clutchcargo and arca_tern like this.
  17. I don’t really want to try again. Soldering isn’t my forte and I had to borrow a buddies iron that did 60 watts to get desolder the wires from the pots. But using electrical tape in that part of the cavity makes sense to see if it was a “jack making contact” issue.

    It is shielded though. When plugged in and the amp cranked and not touching any metal on the bass there is no hiss whereas before it was heinous. I think there’s enough conductive paint along the top edge of the control cavity that it makes contact with the control plate completing the ground.

    My buddy who is not a guitar tech but has played for ages said the same (signal is gong to ground somewhere). Makes sense.
    Yes, it’s wired the same but not as pretty with the solder joints. Haha.

    Yeah I checked beforehand with the multimeter and the control plate was grounded. I knew it should be for the jack mechanically but wanted to confirm. Figured while I was in there why not add some insurance.

    Not preachy at all. If I roll off one of the volumes for sure there is 60 cycle but c’est la vie. What WAS eliminated was the need for me to always be touching metal on my bass to stop hiss through the amp or worse the church sound system. Now I can go full Pentecostal with both hands in the air :laugh:
    bassdude51 and Spidey2112 like this.
  18. FunkyD

    FunkyD Supporting Member

    Mar 16, 2011
    NJ, USA
    But can you wave them through the atmosphere? That's what we need to know.
  19. Missing the reference, sorry.
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